Most forms of steel abruptly become brittle at temperatures below about -25°C unless they are mixed with other metals.

2019年6月六级真题（第三套）阅读 Section A

Rather than adding other metals, they developed a complex mechanical process involving repeated heating and very severe mechanical deformation, known as temp-forming.

2019年6月六级真题（第三套）阅读 Section A

So scientists have strived to find a solution by mixing it with expensive metals such as nickel.

2019年6月六级真题（第三套）阅读 Section A

This is partly driven by the rising price of raw materials and metals.

2019年6月六级真题（第二套）阅读 Section B

Together, the value of these metals is estimated to be about $52 billion.

2019年6月六级真题（第二套）阅读 Section B

A Swiss study reported that while the weight of electronic goods represented by precious metals was relatively small in comParison to total waste, the concentration of gold and other precious metals was higher in so-called e-waste than in nature.

2015年高考英语江苏卷 阅读理解 阅读B 原文

Consider again the cell-phone, and imagine the mines that produced those metals, the factories needed to make the box and packaging (包装) It came in.

2015年高考英语江苏卷 阅读理解 阅读B 原文

Electronic devices contain valuable metals such as gold and silver.

2015年高考英语江苏卷 阅读理解 阅读B 原文

Electronic wastes also contain many poisonous metals.

2015年高考英语江苏卷 阅读理解 阅读B 原文

Even when the machines are recycled and the harmful metals removed, the recycling process often is carried out in poor countries, in practically uncontrolled ways which allow many poisonous substances to escape into the environment.

2015年高考英语江苏卷 阅读理解 阅读B 原文

Natural minerals contain more precious metals.

2015年高考英语江苏卷 阅读理解 阅读B 选项

The percentage of precious metals is heavy in e-waste.

2015年高考英语江苏卷 阅读理解 阅读B 选项